/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
/* Name of the class has to be "Main" only if the class is public. */
class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
        String s;
        s = in.next();
 
        for (int j = 0; j < s.length(); j++) {
            int i = j + 1;
            while(i< s.length())
            {
                if (s.charAt(j) == s.charAt(i) && i!= j)
                {
                    String s1=s.substring(0, i);
                    String s2 = s.substring(i+1,s.length());
                    s=s1.concat(s2);
                }
                else i++;
            }
        }
        System.out.println(s.length());
	}
}

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